China has escalated its violations of South Korea’s air defense identification zone.

A Chinese military plane believed to be a reconnaissance aircraft entered the zone without notice Saturday. It came into the zone from northwest of Ieodo, a submerged rock south of Jeju Island, changed direction toward the eastern island of Ulleungdo before turning back south and exiting the zone on its entry route. It stayed in the zone for about four hours.

An air defense identification zone is airspace in which a country identifies, locates and controls foreign aircraft for its national security. The zone gives the country more time to respond to possibly hostile aircraft. It is an international custom for any aircraft to give 24-hour notice and receive permission before entering the zone. However, China flouts this convention.

China has violated the zone three times this year, including the latest incident. Its violations have gotten bolder. On Feb. 27, a Chinese aircraft flew south of Ieodo but this time it went between the island and Jeju Island. On Jan. 29, a Chinese military plane flew north to 120 kilometers south of Ulleungdo, but in February and this time, it went farther to 30 km north of the island in the East Sea.

A Chinese military plane has flown into the zone without notice whenever the situation of the Korean Peninsula has entered a critical stage. In January, China violated the zone 10 days before the opening of the PyeongChang Winter Olympics. In February, it did so when the South secretly prepared to send envoys to the North to arrange a summit.

The latest incident happened a day after the historic summit between South and North Korea, and attention has now shifted to an upcoming historic summit between the US and the North.

The Chinese military is under the control of the Chinese Communist Party. Therefore, it is a convincing view that the recent encroachment was not simple flight training as Beijing claimed, but rather an act that carried a message.

China is concerned about being sidelined in the process of establishing a peace regime on the peninsula. As a three-nation summit of the two Koreas and the US is expected in June or July, there is a high likelihood that Beijing wants to make its hegemonic presence felt regarding the matter of denuclearizing the North.

Ignoring the zone drawn by South Korea is one of the ways to show its muscle. The violation of the zone is an intentional move apparently to achieve its long-term goal of bringing the peninsula within the area of its influence.

On the surface, China supports the Panmunjeom Declaration, but it probably has many concerns as well.

The rapidly changing situation of the peninsula is driven by talks involving South and North Korea and the US. Some even speculate that China’s influence over the North Korean issue will wane.

From a military viewpoint, China’s habitual violation of the South Korean zone may have something to do with Chinese President Xi Jinping’s plan to make his country a military superpower. Chinese military planes entered the zone without notice about 60 times in 2016 and nearly 70 times in 2017.

Beijing may have been seeking to test South Korea’s airspace defense readiness or the order of Northeast Asia amid thawing inter-Korean relations. The plane may have entered the zone to snoop on South Korea-US military exercises or the construction of the Terminal High Altitude Area Defense anti-missile system.

For what purposes did a Chinese military plane fly to the airspace just about 74 kilometers away from Gangneung, on the coast of Gangwon Province? China is a superpower that places great emphasis on hegemony. Someday, its hegemony may become as threatening to the South as North Korea’s nuclear weapons.

The government in Seoul must deal with this issue seriously and sternly to prevent a recurrence of the incident. Meanwhile, China should act according to its status as a Group of Two superpower.